Western University researchers testing ways to reverse long-term effects of marijuana

Western University researchers may have found a way to reverse the harmful effects that marijuana use can have on teenagers’ brains.

The researchers, in a breakthrough discovery, say they’ve found a way to use pharmaceutical drugs to counter the long-term negative psychiatric effects of tetra­hydrocannabinol (THC), the psychoactive component in cannabis that gives users the feeling of a euphoric high.

Previous research has linked chronic pot use by teens with a range of psychiatric diseases such as schizophrenia later in life, with the risk rising the earlier that young people begin using marijuana.

The Western discovery’s announcement comes days after Ontario became the first province to detail its plans to sell legal marijuana next year, deciding pot will be sold through a separate arm of the province’s LCBO liquor store monopoly and — significantly, for teens — its sale limited to buyers 19 and older, just like booze and cigarettes.

The Western study, published Tuesday in Scientific Reports, demonstrated adolescent THC exposure affects the neurotransmitter called GABA, a chemical messenger previously associated with schizophrenia, in the brain’s prefrontal cortex.

The seven-member research team found that when GABA was reduced by THC exposure in adolescence, neurons in that region of the brain became hyperactive and out of synch, resulting in an abnormal state in the dopamine system that’s commonly seen in schizophrenia.

Using drugs to activate GABA in rats, researchers reversed the effects of THC to eliminate the schizophrenia-like symptoms.

“Even after the damage has occurred in adolescence, if can you effectively target these changes, you can potentially mitigate these negative symptoms and reverse some of these side effects,” said study co-author Steven Laviolette, an associate professor at Western’s Schulich School of Medicine & Dentistry.

Ontario’s plan to sell recreational pot in Ontario calls for a subsidiary of the Liquor Control Board of Ontario (LCBO) to begin selling marijuana at 40 outlets — orders also will be taken online — by next summer, when the federal Liberals are expected to deliver on their vow to liberalize Canada’s pot laws and make recreational use legal.

A task force had recommended 18 be the minimum age to buy marijuana, but provinces have been given free reign to raise the requirement.

Pot’s potential to have lasting psychiatric effects continues into a person’s mid-twenties, said Dr. Laurent Marcoux of the Canadian Medical Association. “There is a high risk because the human brain develops until 25,” Marcoux said, adding not enough is known about the long-term effects of cannabis to introduce the drug for recreational use.

“It’s like 50 years ago with cigarettes,” he said.

Laviolette, who first started researching cannabis 13 years ago at the University of Pittsburgh, said red tape often gets in the way of marijuana work.

“Even the non-psychoactive compounds found in marijuana are listed as narcotics, so you need to get licences, you need to get exemptions,” he said. “I think it scares a lot of people away from actually conducting these studies.”

And then there’s the struggle to source pure THC.

Despite the federal government’s plan to legalize recreational pot by July 1, 2018, Laviolette has to order THC from the U.S., paying around $2,000 a gram for the substance — significantly more than the $10 a gram of pot sells for on the street.

“It can be done, but it’s prohibitive,” Laviolette said of obtaining pure THC.

Lavilette and his research team now will turn their focus exploring how combinations of cannabinoid chemicals can boost the brain’s GABA system as a potential treatment for mood disorders such as addictions, depression and anxiety.

“As we move forward in the biotechnology sphere in developing safer drugs that are based in cannabinoids, we might want to look at compounds that interact with the GABA system to mitigate the potential side effects of THC,” Laviolette said.